Counter-rotating spindle for friction stir welding

Abstract

A counter-rotating spindle includes a shoulder tool, a pin tool inserted in the shoulder tool, a first motor that is connected with the pin tool and rotates the pin tool, and a second motor that is connected with the shoulder tool and rotates the shoulder tool. The direction and the speed of the rotation for the pin tool may be selected independently from the speed and direction of rotation of the shoulder tool enabling optimization of the friction stir welding process. Counter-rotating the pin tool and the shoulder tool may improve the mixing abilities and efficiency of the pin tool and may prevent the galling effect between the pin tool and the shoulder tool. The counter-rotating spindle may be used, for example, for continuous path friction stir welding and spot welding of aluminum and its alloys, including cast alloys, as well as joining similar and dissimilar alloys.

1. A friction stir welding device, comprising:
 a first spindle, the first spindle comprising
 a pin tool, 
 a first collet connected to a back end of the pin tool and inserted into a first tool holder, 
 the first tool holder configured to receive the first collet and to connect the first collet and the pin tool to a first drive spindle, 
 the first drive spindle configured to connect the first tool holder to a first motor, and 
 the first motor connected to the first drive spindle such that the first motor rotates the first drive spindle, the first tool holder, the first collet, and the pin tool around a central axis of the friction stir welding device in a first direction; and 
 
 a second spindle, the second spindle comprising
 a shoulder tool, 
 a second collet connected to a back end of the shoulder tool and inserted into a second tool holder, 
 the second tool holder configured to receive the second collet and to connect the second collet and the shoulder tool to a second drive spindle via a union nut, 
 the second drive spindle configured to connect the second tool holder to a second motor, and 
 a second motor connected to the second drive spindle such that the second motor rotates the second drive spindle, the second tool holder, the second collet, and the shoulder tool around the central axis of the friction stir welding device in a second direction opposite the first direction, 
 
 wherein the first spindle is inserted within the second spindle and is movable along the central axis within the second spindle such that the pin tool extends from and retracts within the shoulder tool while the pin tool and the shoulder tool independently rotate. 
 
   
   
     2. The friction stir welding device of  claim 1 , further comprising a pressure foot clamp assembly configured to capture and retain plasticized material from a hole created by the retractable pin tool while penetrating the work-piece, the pressure foot clamp assembly comprising:
 a non-rotating fixed housing; 
 a spring inserted into an opening of the non-rotating fixed housing; 
 a retaining cap configured to secure to the non-rotating fixed housing, and 
 a pressure foot clamp movably disposed between the spring and an inside surface of the retaining cap such that the pressure foot clamp compresses the spring and displaces linearly upward along the central axis when pressure is applied to a surface of the pressure foot clamp adjacent to an inside surface of the retaining cap. 
 
   
   
     3. The friction stir welding device of  claim 1 , wherein the shoulder tool has a cylindrical shape, a front end, and a back end, and extends longitudinally along the central axis, wherein the shoulder tool is hollow and has an inner diameter, wherein the shoulder tool includes a front section and a back section, wherein the front section has a smaller diameter than the back section, and wherein the front section and the back section form a shoulder. 
   
   
     4. The friction stir welding device of  claim 1 , wherein the retractable pin tool has a cylindrical shape, the front end, a back end and an outer diameter and extends longitudinally along the central axis, wherein the outer diameter is smaller than the inner diameter of the shoulder tool, wherein the retractable pin tool includes a pin, and wherein the pin extends from the shoulder tool. 
   
   
     5. The friction stir welding device of  claim 4 , wherein the pin is threaded. 
   
   
     6. A friction stir welding device, comprising:
 a shoulder tool; 
 a retractable pin tool inserted in the shoulder tool, wherein the retractable pin tool is movable inside the shoulder tool along a central axis while rotating independently from the shoulder tool; 
 a first motor connected with the retractable pin tool and operative to rotate the retractable pin tool in a first direction; 
 a second motor connected with the shoulder tool and operative to rotate the shoulder tool in a second direction opposite the first direction, 
 wherein the friction stir welding device is configured to retract the retractable pin tool from a work-piece being welded while the shoulder tool maintains contact with the work-piece; and 
 a pressure foot clamp assembly configured to capture and retain plasticized material from a hole created by the retractable pin tool while penetrating the work-piece, the pressure foot clamp assembly comprising
 a non-rotating fixed housing, 
 a spring inserted into an opening of the non-rotating fixed housing, 
 a retaining cap configured to secure to the non-rotating fixed housing, and 
 a pressure foot clamp movably disposed between the spring and an inside surface of the retaining cap such that the pressure foot clamp compresses the spring and displaces linearly upward along the central axis when pressure is applied to a surface of the pressure foot clamp adjacent to an inside surface of the retaining cap.